1. Field of the Invention
The present invention relates to electronic circuits and, more specifically, to an electronic circuit that increases the difficulty associated with reverse engineering.
2. Description of the Prior Art
Reverse engineering is a common way for someone to misappropriate technology, such as electronic circuits. Typically, the reverse engineer disassembles an apparatus to determine how its component parts interact. In the case of application specific integrated circuits (ASICs), a reverse engineer may cut off successive layers of a circuit package and image them to determine the placement of the various circuit components that make up the ASIC.
One way to guard against reverse engineering is to include a plurality of anti-tamper fuses in critical data paths of a circuit. The fuses are coupled to a tampering detection device that causes the fuses to blow when the circuit is being tampered with. Since the fuses are in a critical data path of the circuit, the blowing of the fuses causes the circuit to malfunction.
Certain imaging systems, such as thermal imaging systems, allow a reverse engineer to make an image of internal portions of a circuit without having to cut into the circuit, or otherwise trigger a tampering detection device. The reverse engineer is able to examine the image of the circuit to determine both placement of the circuit elements and the fuses. By replicating the circuit elements and the fuses, or by replicating the circuit elements and replacing the fuses with short circuits, the reverse engineer is able to replicate the functionality of the circuit.
Such reverse engineering can cost circuit manufacturers considerable losses through misappropriation of trade secrets. Also, reverse engineering can result in the loss of classified information about the operation of military circuits.
Therefore, there is a need for a system that frustrates reverse engineering of circuits through the use of imaging systems.
There is also a need for a system that renders a reverse engineered circuit inoperable.